hey fre2e

Good to see u here again
Not sure if that has to do with Windows 7, but try this. I myself use Windows Vista, which also gets unusual errors that Window XP never does.
Classic games aren't meant for Vistas and 7, and I know it sucks.
Just download Daemon tools lite, or just google Daemon. Bin is an image file that needs to be unextracted, but not by Winzip

Once you get the Daemon, click on virtual CD Rom, then Device (should be more than 1 device), and simply mount the image. Click the bin file and mount it. Now either click on the Mount/device manager, or go to "my computer". You will see BG2 is installed.
It's best advised that you find this instruction from google, which shows proper illustration. It's kinda hard to understand what I just typed above, because Daemon tool displays a button with picture, not with a letter, unless u put mouse cursor on it and wait till it shows the description.